[build] Check that mkisofs equivalent supports the required options

The "-e" option required for creating EFI boot images is supported
only by widely used patched versions of genisoimage.

Check that the required options are supported when selecting a mkisofs
equivalent, thereby allowing a fallback to the use of xorrisofs when
building a UEFI ISO image on a system with an unpatched version of
genisoimage.

Continue to prefer the use of genisoimage over xorrisofs, since there
is apparently no way to inhibit the irritatingly useless startup
banner message printed by xorrisofs even when the "-quiet" option is
specified.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/util/genfsimg

@@ -171,23 +171,6 @@ case "${OUTFILE}" in
 	SYSLINUXCFG="${FATDIR}/syslinux.cfg"
 	;;
 esac
-ISOARGS=
-
-# Locate required tools
-#
-if [ -n "${ISOIMG}" ] ; then
-    MKISOFS=
-    for CMD in genisoimage mkisofs xorrisofs ; do
-	if ${CMD} --version >/dev/null 2>/dev/null ; then
-	    MKISOFS="${CMD}"
-	    break
-	fi
-    done
-    if [ -z "${MKISOFS}" ] ; then
-	echo "${0}: cannot find mkisofs or equivalent" >&2
-	exit 1
-    fi
-fi
 
 # Copy files to temporary working directory
 #
@@ -240,6 +223,7 @@ done
 # since isohybrid will refuse to work without them.
 #
 if [ -n "${ISOIMG}" ] ; then
+    ISOARGS="-J -R"
     copy_syslinux_file "isolinux.bin" "${ISODIR}"
     copy_syslinux_file "ldlinux.c32" "${ISODIR}" || true
     ISOARGS="${ISOARGS} -no-emul-boot -eltorito-boot isolinux.bin"
@@ -276,11 +260,22 @@ fi
 # Create ISO filesystem image, if applicable
 #
 if [ -n "${ISOIMG}" ] ; then
+    MKISOFS=
+    for CMD in genisoimage mkisofs xorrisofs ; do
+	if "${CMD}" ${ISOARGS} --version "${ISODIR}" >/dev/null 2>&1 ; then
+	    MKISOFS="${CMD}"
+	    break
+	fi
+    done
+    if [ -z "${MKISOFS}" ] ; then
+	echo "${0}: cannot find a suitable mkisofs or equivalent" >&2
+	exit 1
+    fi
     "${MKISOFS}" -quiet -volid "iPXE" -preparer "iPXE build system" \
 	    -appid "iPXE - Open Source Network Boot Firmware" \
-	    -publisher "ipxe.org" -sysid "iPXE" -J -R -o "${ISOIMG}" \
+	    -publisher "ipxe.org" -sysid "iPXE" -o "${ISOIMG}" \
 	    ${ISOARGS} "${ISODIR}"
-    if isohybrid --version >/dev/null 2>/dev/null ; then
+    if isohybrid --version >/dev/null 2>&1 ; then
 	isohybrid "${ISOIMG}"
     fi
 fi